The present invention relates to an autoinjector.
Autoinjectors are well known in the prior art. The main aim of these devices is to carry out automatic injection of the contents of a syringe inside the body of a patient. There are various systems for automating penetration of the needle into the body of the patient as well as injection of the fluid product contained in the syringe. Autoinjectors are relatively complex devices which must respond to a certain number of requirements of stresses to be reliable. The robustness of the device, its handling, and its ease of use for the user are also important elements. In addition, as the majority of these autoinjectors is single use, the cost of manufacture and assembly is also a factor to be kept in mind.
There are numerous autoinjectors on the market, all of which however have some disadvantages.
Therefore, to prevent untimely triggering of the autoinjector, for example during transport or storage, devices must comprise reliable locking means. Similarly, when a user wants to utilise the autoinjector and unlocks the device, for example by removing the cap, the device must not actuate prematurely but only when the user really wants it, that is, at the moment when he applies it to the part of the body in which he wants to carry out the injection. Now, especially when those people using the autoinjector are elderly or handicapped people, it can happen that the user drops the device just when he wants to use it. It is preferable in such a case that the autoinjector does not actuate on its own. It is therefore important to provide a reliable triggering lock. From another viewpoint, using the autoinjector should not become too difficult, which would prevent weak people from using it. It is therefore difficult to find a good compromise between the security of the locking and the ease of use and actuation of the autoinjector. It is one of the aims of the present invention to respond to this problem.
In addition, according to the volume of the fluid product distributed during injection and also as a function of its viscosity, the time needed to complete this injection can be fairly substantial, and may especially exceed several second. It is very important that the user not remove the device from his body before the injection is complete. It is therefore preferable for the device to comprise means for indicating reliably to the user that the injection is finished.
It is also important to ensure that the product is injected to the correct depth in the body, that is, in the right tissue. So mastering the start of injecting, to ensure that the latter will start only when the needle reaches its definitive pricking position, is therefore also an important aspect.
Also, to avoid any risk of injury after use of the device, the autoinjector must comprise a needle safety device which prevents the needle from being conspicuous after use of the device. This safety device must obviously also be reliable and not be released too easily. It must also be functional even if the user improperly activates the autoinjector, for example if he removes it too early from his body, prior to completion of the injection.
Another important aspect of autoinjectors, especially when the volume of fluid product is relatively large and/or when the fluid product injected is relatively viscous, is to allow the product to diffuser from the injection site for a few seconds after said injection. If the user removes the autoinjector immediately after the end of the injection, part of the product can flow back out of the body of the user, which diminishes the efficacy of the treatment. It is therefore preferable to provide that the user holds the autoinjector against his body for a few more seconds after the end of the injection. This aspect is generally resolved by existing autoinjectors by the notice of use which asks the user to count in his head for a certain number of seconds before removing the device. This is not reliable and therefore unsatisfactory, as the system then depends on the user himself who in some cases can be perturbed or weakened by what he has just done.
Documents WO2012045833, EP1743666, WO2009095701, WO2012022810, EP2399632, FR2884722, WO9632974, WO2012000832, US2008281271, WO2009040602, WO2009040604, WO2009040607, WO2010108116, WO2011048422, EP2399628, WO2008112472, WO2011101380, WO2011101382, US2005273055, FR2905273, WO2009062508, WO2009037141 and GB2463034, describe devices of the prior art.